Can't get rid of extra internal face edges to have models ready as STL for 3d printing, please help

Solid inspector 2 says I have extra internal face edges. I want one solid per component, but there seems to be more. How do I get rid of the extra internal face edges? Can you give me some advice please? My intent is to 3d print each individual conveyor belt for my uni project and then I would just attach them together myself with glue. I just can’t get my head around this STL part.
conveoyors only for 3d print.skp (15.4 MB)

I have a uni deadline and I am panicking because I need these to be an STL file ready for 3d printing for Monday!! I have spent hours trying to get this to work and I am close to giving up.

You need to make your parts groups or components and then run solid inspector on them.
All your straight parts can easily be made into solids, triple click to select all connected, right click and make group or component. Then use solid inspector to fix the internal faces and reversed faces.
The curved sections need work as many of the rollers are not correctly connecting to the rest of the geometry. I also suspect that the rollers on a curve don’t taper, nor would they be oval. They are more likely to be arrayed so that they are spaced further apart on the outside of the curve , but I’m only guessing.
GIF 26-04-2024 10-54-10 AM

You can use a circle to make an array of rollers and choose the ones you want for each bend and just add the rails. I didn’t bother with the rails, but a simple follow me would make them. There is a small error in this, I did the rotate copy 4 deg then 90 times (4x90=360) but I should have done 89 times so there would be a double at the start point.
GIF 26-04-2024 11-12-08 AM

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(above is a screenshot of your GIF) I can’t see this option to type. I’m using SU 2024

Also would I be able to create the beam for these rollers and which one do I start with first? I am a very slow learner so please bear with.

The measurement box is by default in the bottom right corner of the workspace, you don’t click in it to type, you just type and it is displayed there.

You need to learn about the follow me tool and creating arrays with the move tool and the rotate tool.

Here is a basic demo of making a 90 degree track, note I rotate the circle half a segment so the path for follow me is perpendicular to the Profile.
I can’t do any more than this as I’m about to get in my car for a 5 hour drive and won’t be back to my PC for several days. Definitely not before your assignment is due.
GIF 27-04-2024 9-57-36 AM

A last thing, if the rollers extend into the rails properly ,not just touching but fully into the rail, you can make the Rails solid then use Outershell to make the whole thing a solid.
The only thing offscreen in the gif is Make Group when I grouped the rails.
Nothing I have done here can’t be done in any version of sketchup.
GIF 27-04-2024 10-07-44 AM

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Thanks for the reply -

The bend on my version doesn’t seem to be smooth but instead appears more edged. How do I fix that?

Then you should start with an arc with more segments.
The radius of the rollers, their spacing on the inside, the overall angle of the curve, they all should match and together they determine the lowest possible number of segments.
See what you get with one roller per segment to see if that would make a smooth enough curved beam.

I’m beginning to give up, I’ve set the arc segment to 100, created a roller at the beginning of the curved beam but they never align properly when duplicating them from the same curve I made to make the beams. Lowered the segment to 50, still the same. I can make the beam without a problem, it’s the rollers that’s giving me a headache.

P.s I have no Outershell option and I tried copying user Box’s (thank you for helping by the way) way of this from the GIF’s but ‘weld edges’ doesn’t seem to do anything on my end.
conveyors.skp (9.8 MB)

Are you really using SketchUp for Schools as your forum profile says?

How many rollers do you want on the quadrant of your conveyor?

I’ve changed this to the correct version.

18-20 rollers for top and bottom

Thank you.

And you do have Outer Shell in the Tools menu. It won’t do you any good unless all your geometry is combined into objects that are recognized as solids.

Settle on the number of rollers you want and use a number for the number of sides in the arcs that is a multiple.of that number. So for 20 rollers, 40 or 60 sides.

Don’t bother with Outershell anyway. You don’t need it for this model. Since the rollers aren’t going to actually roll, just make them as a solid component or group and make the rails a solid component or group. Here’s an example. All of the rollers are in one component. The rails are in a second component. They are both identified as solid objects in SketchUp.

In a plan view and X-ray face style you can see that the roller geometry extends into but not all the way through the rails.

And here’s what it looks like in the slicer.

Thanks for all your help, I have got it working now!

This is brilliant!! Had to set the number of arc sides to 80 for 20 rollers to fit snug. I then intersected faces with selection so I could delete each roller face and when I checked using Solid Inspector, there were no errors… I feel like a complete newb, but we start somewhere. Thanks again.

You missed an important point in my previous post. There’s no need to do the intersections and erasing faces in this case. Leave them as two separate solid object. Less work and easier to modify later if you need. Here I quickly changed the number of rollers from 18 to 20 by simply editing the roller object.